ing an altitude of 2400 feet at only one point on the S.E., while
elsewhere it is scarcely higher than that of Lubiniezky. It is clearly
polygonal, approximating to the hexagonal type. On the more distinct S.
section a bright spur projects from it. On the N. its continuity is
broken by a distinct little crater. It is traversed by a remarkable white
streak, extending in a S.W. direction from Bullialdus C (where it is very
wide), across the interior, to the more westerly of two craters S.W. of
Mercator. Another streak branches out from it near the centre of the
floor, and runs to the W. wall. The principal streak, so far as the
portion within Kies is concerned, represents a cleft. On the Mare E. of
Kies is a curious circular mound, and farther towards Campanus two
prominent little mountains. On the N.W. is a large obscure ring and a
wide shallow valley bordered by ridges.

AGATHARCHIDES.--A very irregular complex ring-plain, about 28 miles in
diameter, forming part of the N.W. side of the Mare Humorum. It must be
observed under many phases before one can clearly comprehend its
distinctive features. The wall is very deficient on the N., but is
represented in places by bright mountain masses. The formation is flanked
on the E. by a double rampart, which is at one place more than 5000 feet
in height, with a deep intervening valley. The S. wall is traversed by a
number of parallel valleys, all trending towards Hippalus. These are
included in a much wider and longer chasm, which, gradually diminishing
in breadth, extends up to the N. wall of the latter.

HIPPALUS.--A partially ruined walled-plain, about 38 miles in diameter,
on the W. side of the Mare Humorum, S. of Agatharchides. At least one-
third of the border is wanting on the S.E., but under a low sun its site
can be distinguished by a faint marking and the obvious difference in
tone between the dark interior and the lighter-coloured plain. The rest
of the wall is bright and continuous, except at a place on the W., where
what appears to be the segment of a large ring has encroached upon it.
There are two craters in the interior of Hippalus, and a row of parallel
ridges, running obliquely from the S.W. wall up to a cleft which
traverses the floor from N. to S. W. of Hippalus stands a bright crater,
Hippalus A, with an incomplete little ring-plain adjoining it on the
N.W.; and N.E. of it a much larger obscure ring containing two little
hills. The Hippalus rill-system is a